Objective To prepare cod soup using cod as the main raw material by microwave heating, with traditional boiling as the control, and to compare and analyze the effects of microwave decocting on the release law of flavor substances in cod soup.Methods Cod soup was processed at different durations (15, 30, 45, and 60 min), followed by sensory evaluation. The changes in the contents of trichloroacetic acid (TCA)-soluble peptides, amino acid nitrogen, flavor nucleotides, organic acids, inorganic salt ions, and free amino acids in the soup were analyzed.Results The contents of TCA-soluble peptides, amino acid nitrogen, flavor nucleotides, organic acids, and inorganic salt ions (Na⁺, K⁺, PO43-, and Cl^-) all increased with the extension of decocting time, and were significantly higher in the microwave decocting group at 60 min than in the traditionally boiled group at 60 min (P<0.05). The sensory score, total flavor nucleotides, total organic acids, and total free amino acids all reached their highest values at 60 min of microwave decocting. The electronic nose and electronic tongue effectively distinguished the soups prepared by the two boiling methods. A total of 80 volatile compounds were identified by GC-MS, among which aldehydes, esters, and ketones were the main contributors to flavor differences. Microwave heating promoted the formation of aromatic aldehydes, ketones, esters, and some alcohols.Conclusion Microwave decocting is more conducive to the increase of taste compounds and volatile flavor substances in cod soup, and makes a significant contribution to the overall flavor profile of the soup.